Living body information measurement devices are known which can measure living body information such as a pulse rate and a blood pressure using information that is detected by a pressure sensor in a state that the pressure sensor is in direct contact with a living body part where an artery such as a wrist radius artery runs (refer to JP-2007-319343-A and JP-H02-261421-A, for example).
JP-2007-319343-A, JP-H02-261421-A and JP-H01-242031-A disclose blood pressure measurement devices which measure a blood pressure for each beat without using a cuff, that is, using only information detected by a pressure sensor that is set in contact with a wrist.
As disclosed in JP-2007-319343-A, JP-H02-261421-A and JP-H01-242031-A, measuring a blood pressure using only information detected by the pressure sensor that is set in contact with a living body makes it possible to miniaturize the device. The devices disclosed in JP-2007-319343-A and JP-H02-261421-A are such that a blood pressure is calculated by calibrating a pressure pulse wave that is detected by the pressure sensor in a state that the pressure sensor is pressed by an optimum pressing force.
In the devices disclosed in JP-2007-319343-A and JP-H02-261421-A, it is necessary to separately obtain, in advance, using a cuff or the like, data to be used for calibrating a pressure pulse wave detected by the pressure sensor. As a result, where the device is shared by plural users, calibration data needs to be obtained for each user by a certain method. However, since the device cannot generate such calibration data by itself, the users cannot start blood pressure measurements easily.
On the other hand, in the device disclosed in JP-H01-242031-A, blood pressure values are calculated on the basis of a variation of the amplitude of a pressure pulse wave that is detected in a process that the pressing force of the pressure sensor is varied continuously and calibration data is generated using these blood pressure values. As a result, a continuous blood pressure measurement can be started in a short time without causing a user to feel troublesome.
In devices of such a type as to be attached to a wrist as in the one disclosed in JP-H01-242031-A, a large difference may occur between a state of a device attachment part when calibration data was generated and a state of the device attachment part when a continuous blood pressure measurement is performed. In JP-H01-242031-A, no consideration is given to this problem.